Fuse



E. W. BRANDT Oct. l, 1963.

FUSE' Filed Dec. 29, 1960 Octl, 1963 E. w. BRANDT 3,105,440

FUSE

Filed Deo. 2s, 1960 4 Sheets-Sheet E. w. BRANDT- Oct. l, 1963 FUSE FiledDec. 29, 1960 Oct. l, 1963` E. w. BRANDT 3,105,440

FUSE: Filed Dec. 29, 1960 4 4 sheets-snee@ 4 United States Patent Onliceassai Patented Got. l, i953 3,105,440 FUSE Edgar William Brandt,deceased, late of Geneva, Switzerland, by Paul Emile Denoix, executor,Geneva, Switzerland, assigner to Anstalt fiir die Entwicklung vonErfindungen und gewerblichen Anwendungen ENERGA, Vaduz, LiechtensteinFiled Dec. 29, 1960, Ser. No. 79,462 Claims priority, applicationSwitzerland Jan. 29, 196i) 1 Claim. (Cl. 102-52) This invention concerns-a fuse intended primarily for use in hollow charge projecticles.

The fuses heretofore proposed for use in hollow charge projectiles canbe `divided into three `distinct categories, namely inertia base fuses,fuses functioning by compress-ion (possibly by compression and inertia)and electric fuses.

Inertia base fuses are, in general, only slightly sensitive and have, atimpact, an appreciable delay in firing, especially lat large firingincidences, since they necessitate the braking or the stopping of theentire m-ass of the projectile before percussion. Attempts have beenmade to remedy these disadvantages by reinforcement of the lthe strengthof the cap and of the body of the projectile which supports it with aview to reducing deformation of the projectile at impact Iand the ldelayin the functioning by inertia, but these arrangements involve anappreciable increase in weight with the disadvantages which relatethereto.

Percussive fuses, which function by compression, or by compression andinertia, avoid, to a large extent, the aforementioned defects and cancomprise very light plungers provided with a hard head of small sizeallowing the instantaneous functioning against armor-plating, even atlarge firing incidences.

lt can happen, however, that the projectile touches the target -at aperipheral point on its cap without there being contact Iand compressionof the plunger. The danger yof non-.functioning is increased by the newdefenses discovered for combat vehicles with a View to causing thedislocation of the hollow charge projectile; braking, stopping ornon-functioning can also result on obstacles such as grilling, pins,inde-mations, and the like, Without the plunger of the fuse being eithercompressed or actuated by inertia where the latter is provided.

Hence it has been proposed to provide hollow charge projectiles withelectric Ifuses which factulate a detonator on impact. But devices ofthis type are complex, costly, and diiiicult to construct. Furthermore,they require movable conta-cts and insulation, defects of which canoften be the cause of vfailure to function, so that it is generallynecessary to add electro-mechanical safety devices which make them heavyand cumbersome.

The present invention has for its object to remedy the aforementioneddisadvantages. According to the invention there is provided a fuseprimarily intended 'fo-r use in a hollow charge projectile andpositioned in front of a char-ge, wherein the fuse comprises at leastone percussive device yand tiring elements and wherein the percussivedevice comprises a peripheral collar of a diameter near to that of theprojectile and having at its front an edge harder than currentarmor-plating, said collar being fixed on a rigid support of which thecentral part is adapted to contr-ol the action of one of the tiringelements on impact of the projectile against a target.

By this mea-ns a tuse may be constructed of which the percussive 4deviceconstitutes an assembly of mass small with respect to that of theprojectile, this assembly being is capable of causing, at the center ofthe percussive device, a relative movement assuring the functioning of adetonator fuse and consequently the transmission of the iiriug .to aprincipal detonator 'for the explosive charge.

Preferably, the peripheral collar of the 'fuse is constituted by 1a bandof case-hardened steel, and can be force-iited, screwed, glued or set ina housing of the percussive device.

The percussive device is retained iannularly by at least one elementdeformable or shearable on impact so that only this device is stopped`on the target, the principal mass of the projectile maintaining itsspeed until percussion.

ln a particular embodiment of the invention, there can be added a systemfused by a relay-detonator iixed :axially on a support integral with theprojectile but independent of the detonat-ing fuse and the percussivedevice. lt results from this arrangement that, on impact, even if thedetonating fuse is thrust obliquely by lthe relative movement of thepercussive device, the transmission of the `tir-ing emanating yfromtherelay-detonator remains .centered along the axis of :the projectile.

A ballistic cap, yformed in one or several parts of a generallycylindre-ogival form, acts as an annular support 'for the percussivedevice. This cap assures the protection of the Ifuse in case of lfall inthe course of transportation and handling as well las its completesealing.

Preferably, an `annular setting of the cap, possibly in zones or atpoints, retains the percuss-ive device in position; this setting canconstitute, by itself, the deformable element which gives way on impactof the peripheral collar on the target.

ln one modification, the element deformable on impact is an enevelopewith a generally cylindrical form which is fixed in front of the hollowcharge yand which has a series of annular corrugations.

The fuse may be completely housed in a cylindrical part of a ballistichousing arranged on the -front of the projectile so that the ogival nosecontributes to the safety in falling and a deformation of this, even yasubstantial one, does not cause percussion. The ogival nose constitutesat the same time, as shown by tests, a safety chamber the Wall of whichdoes not `give way, under the force of an unforseen shock, to untimelyfunctioning of the detonating fuse. This characteristic, added to thefact that the hollow charge projectile can comprise a supplementarysafety device arranged behind the summit of the perforation cone,prevents bursting of the cap from reaching the lirer or the gun crew, aswould be possible in the absence of this arrangement.

The percussive device may be made independent from the ring elements sothat the direction of displacement on impact of this device does notaffect the axial movement of the plunger, the point of which remainsdirected towards the center of the fuse. To this end, the plunger andthe fuse-cap can be mounted at the top of a rigid support independentfrom the percussive device. If the projectile hits the target at a large'angle of incidence, the percussive device tends to begin a movement ofrotation `about a point diametrically opposite to that of the impact andcontstitutes a lever the central part of which acts, in the manner of apush rod, on the plunger. The latter, guided and centered in the plungerygate is only actuated by the axial component of the displacement of thepercussive device.

With a View of reducing as much as possible the transverse component ofthe movement of the percussive device, the central part of the latter isarranged at a very small distance (l to 2 millimetres) from the head ofthe plunger.

However, the plunger and the fuse-cap may, on the contrary, be integralwith the percussive devices, only a spacing member of synthetic plasticor elastic material retaining the detonating fuse at a suitable distancefrom the point of the plunger. rlhis arrangement gives the fuse a highsensitivity, since on impact it can function at the same time bycompression and by inertia of the detoniating fuse which falls on theplunger. T he relaydetonator assures the axial transmission of thefiring to the principal detonator.

The fuse of the present invention functions when the rojectile touchesthe target at any point whatsoever of its ogival cap and this even at avery large angle of incidence of impact. This characteristic resultsfrom the fact that the percussive device has a diameter near to that ofthe projectile, and from the fact that it is designed -to bitelmomentarily `into the target, thus to stay there fixed and stoppedywithout sliding or rebounding. Moreover, the mechanico-pyrotechnicassembly lis such that it functions whatever may be the direction of thedisplacement of the percussive device on impact, with respect to theaxis of the projectile, the percussive device necessarily causing, byone of the aforementioned means, the axial transmission of the ring tothe principal detonator.

Hfhe safety of the fuse in the course of transportation and handling isassured by the ballistic cap which, in the case `of the projectilefalling on its head, can be deformed for a sufficient distance, withoutinteraction with the percussive device. Furthermore, a `safety mechanismwith automatic retraction at the start of the shot can be added to saidfuse, if so desired.

In lanother modification, the percussive device instead 'of beingsupported by the ballistic cap of the projectile is retained on asupplementary interior cap by an annular flange of `small strength whichis deformable or shearable on impact. In this arrangement, -a smallannular space is provided between the percussive device and theballistic cap so that the latter acts as a protective device for thefuse.

The plunger, which is of Very small mass, can be either integral withthe percussive device or independent thereof. In the latter case, theplunger is centered and suspended, with regard to the detonating fuse,by at least one element, for example a washer shearable or deformableunder the action ofthe percussive device which, at the impact, knocksagainst the head of the plunger. Preferably, a prepiheral space isprovided between the wall of the fusecap and the plunger so that duringthe operation, the latter is not submitted to any rubbing.

lIn a particular modification, a safety system is incorporated in thefuse, the safety system being retractable at the beginning of the yshotand, until then, being interposed between the plunger and the centralpart of the percussive device.

The safety system can be constituted by an assembly of cylindricalsegments housed in an annular inertia block, the said segments beingthrust radially towards the exterior by an opposed member, such as aspring or the like. The falling back `of the inertia block at the startof the shot causes the lateral drawing aside of the segments under theeffect of the member.

As mentioned above, the ballistic cap may surround the percussive fuse,and with a view to increasing las much as possible the incidence offunctioning of the percussive device, the cap must at least comprise anannular zone of small thickness and strength in front of the peripheralcollar. It results from this that, on impact, the said cap is easilycrushed at its point of contact with the target and that the peripheralcollar, thus uncovered, bites into the target.

With a view to making the firing elements easily removable, thepercussive device can be effectively integral with a case containing thefuse-cap, the said case being engaged in the anterior part of theballistic cap. If the fuse is further provided with a r'elay-detonator,

i this can be connected to said fuse-cap by a fiexible connectingelement. it results from these arrangements that by extraction of thesaid case, it is possible to withdraw the fuse at the same time as thedetonator fuse and the relay-detonator.

lin order to enable the invention to be more readily understood,reference will now be made tothe accompanying drawings, which illustratediagrammatically and by way of example some embodiments thereof, and inwhich:

FIG. 1 is an axial section of a hollow charge projectile provided with afuse,

FIG. 2 shows in axial section part of a modification of the hollowcharge projectile shown in FIG. l,

FiG. 3 shows on an enlarged scale and in axial section a detail of FIG.2,

FiG. 4 shows in axial section a modification of the projectile shown inFiG. 2,

HG. 5 shows in axial section another modification of the projectileshown in FIG. 2,

FiG. 6 shows in axial section a detail of FIG. 5, and

FiGS. 7 to l0 illustrate schematically the functioning of the fuse inthe hollow charge projectile.

Referring now to FIG, l, there is shown a hollow charge projectilecomprising an envelope 1, in the interior of which is disposed anexplosive charge 2 and a metallic cone 3 lining the cavity of saidcharge. A support i with a generally conical form is fixed at its base 5on the periphery of the hollow charge, and is provided at its centerwith a fuse-cap 6 in which there is screwed at a detonating fuse 8. Awasher 9, set in the head of the fuse-cap 6, retains a plunger 10 ofvery small mass, the position of which is at a suitable distance fromthe detonating fuse, a peripheral space 11 occurring between the plungerl@ and the fuse-cap 6.

The percussive device comprises a plate or support l2, of light metal,which has a diameter close to that of the caliber of the projectile andwhich has an annular housing in which is force-fitted a peripheralcollar 13 which, however, may alternatively be crimped or glued inposition. The collar 13, which is made, for example, of case-hardenedsteel, is provided at the front with an edge 1d intended to bite intothe target on impact by incidence.

An interior cap 15 concentric with the support 4 supports the percussivedevice through the intermediary of an annular piece i6 retained bycrimping at 17 on the cap i5'. Tongues i8, integral with the piece 16and folded back at a right angle towards the outside, support thepercussive device at its base. These deformable tongues .is of smallstrength permit, on impact with the target, a relative movement of thepercussive device with respect to the principal mass of the projectileand the percussion of the fuse 8 by the plunger it). The assembly of thefuse shown in FIG. 1 is surrounded by a ballistic cap 20 of smallthickness, the rear part of which completely surrounds the fuse and iscylindrical, whilst the forward part of the cap 2t) is ogival. The capZu can be fixed on the projectile by crimping of the envelope 1 at 21.It will be noted moreover that a small annular space is provided betweenthe percussive device 12, 13 and the ballistic cap 20 so that the latterplays the role of a protection member for the fuse.

In the modication shown in FIGS. 2 and 3, the ballistic cap is formed intwo parts, an ogival part 22 and a cylindrical part 23, and supports thepercussive device. An annular crimping 24 (possibly in zones or atpoints) of the ogival part 22 in a peripheral groove of a plate 2S,retains the percussive device in position. The crimping 2li itselfconstitutees, in this modification, the deformable element which givesway on impact of the peripheral collar 13 on the target.

The fuse inclundes a safety system retractable at the start of the shotand, up till then, interposed between a plunger 26 and a central part 27of the percussive device. This system is constituted by an assembly ofsegments 28 housed in an annular inertia block 29 having elastic tongues39 engaging the segments 2S. The segments 28, the bases of which rest onan anterior edge 31 of a fuse-cap 32, are thrust radially towards theexterior by a spring or like member 33. At the start of the shot, theinertia block 29 falls back and its tongues 39 free the segments 2Swhich are forced aside laterally under the effect of the spring 33 sothat the fuse is armed.

In the modification shown in FIG. 4, a plunger 55 and a fuse-cap 56 aremounted on a percussive device comprising a plate or first rigid support5ft, and a peripheral collar 57, a spring 59 retaining a detonating fuseor primer 69 at a suitable distance from the plunger. The faces of theactive edge of the peripheral collar 57 preferably form an angle of 90.

`On impact, the fuse shown in FIG. 4 can function at one and the sametime by compression of the percussive device 57, `5S and by inertia ofthe primer 60 which falls on the plunger 55. Contrary to the embodimentsshown in FIGS. 1 to 3 and 5, the peripheral collar 57 is external tothe'ogival cap 61 so that it directly contacts the target on impact ofthe projectile. For this purpose, the support `S8 of the percussivedevice comprises towards the from an annular extension 62 into a grooveof which there is set at 63 the base of a cap 61. The element deformableon impact is constituted by ,a cylindrical envelope 64 which is providedwith corrugations 65 and which carries the percussive device 57, S.

A relay-detonator 66 is fixed axially on a second support 67 mounted onthe projectile, but independent from the percussive device 57, 5S of thedetonator fuse 6! and the plunger 55. It results from this arrangementthat, on impact of the peripheral collar S7 on the target, thetransmission of fire emanating from the relay-detonator 66 remainscentered along the axis of the projectile, even if the fuse 60 is thrustobliquely by the relative movement of the percussive device 57,58. Aremovable hood 64a, for example of plastic material (shown in-dot-dashlines in FIG. 4), covers the anterior part of the projectile andprovides supplementary protection for the fuse.

FIGS. 5 and 6 show a modifictaion ofy the fuse shown in FIG. 4, and inthis modification the firing members, namely, a plunger 68, a fuse 69and a relay-detonator 79 are easily removable. To this end, theprimer-holder 71 is xedly secured in one end of a case 72 screwedaxially on the percussive device. The case 72, which is open at thefront, is engaged in an orifice in a cap 73 and is centered 'by a rim 74defining the orifice in the cap. A plug 75, for example of plasticmaterial, blocks the open end of the case 72 and assures the sealing ofthe fuse. The primer-holder 71 is linked to t-he relay-detonator 70through a flexible connecting member 76, fixed at 77 on theprimer-holder 71 and at 78 on a collar 79l into which there is screwedthe relay-detonator 70.

The collar 79 is fixed and centered inthe axial part 0f a second support80 of conico-cylindrical form. By unscrewing the case 72, heldat 81 onthe percussive device, the aforementioned elements of the firing devicecan be extracted in a single operation. The connecting element 76 issufficiently fiexible and deformable for the relay 70 supported by thesupport 89 to remain centered and oriented in the axis of theprojectile, even if the fuse 69 is thrust obliquely by the impact of thepercussive device.

FIG. 6 shows on a larger scale, the fuse-cap 71 in front of which thereis set the head of the plunger 68. The detonating fuse 69 is retained ina truncated housingV 82 by a spring or spacing element 83 lthe lowerSpiral of which bears 011 the annular rim 84 of a ceu,-

, of the hollow charge.

tering piece engaged at 85 on the fuse or primer 69. The peripheralspace between the f-use 69 and the wall of the housing 32 limits rubbingand facilitates the travel of said primer on impact of the projectile.

FIGS. 7, 8, 9 and 10 illustrate schematically the functioning of a fuseaccording to the invention:

During normal impact (FIG. 7), the cap 92 is crushed and the percussivedevice 93 is `arrested on the target, while the principal mass of theprojectile continues its travel and while the fuse 94 falls onto theplunger 95. The functioning of the fuse 94 causes that of the relay 96and the firing of the principal detonator (not shown) If the projectilehits the target at a large angle of incidence (FIG. 8), the peripheralcollar, of material harder than current amor-plating, bites at 97 intothis target. The eccentricity of the percussive device 93 does notprevent the transmission of fire to relay 96. The latter in fact remainscentered along the axis of the projectile, since it is mounted on anindependent support which does not undergo any action of the percussivedevice. The fuse operates equally on the ground, on a soft target(earth, mud, ete), as shown in FIG. 9 since the mass of the percussivedevice is very small with respect to that of the projectile and for thisreason has a negligible inertia on impact.

On the other hand, the safety of the fuse, in the course oftransportation and handling, is assured by the ogival ballistic cap 92which, in the case of the projectile falling on its lhead, can bedeformed to a sufficient extent (FIG. l0) without interaction with thepercussive device. It will be noted that the envelope 98 on which thepercussive device is fixed is more resistant than the cap 92 so thatonly the latter is deformed in the case when the projectile falls ontothe ogival cap.

In the embodiments of the invention described above,

the fuse is shown in the head of hollow charge projectiles (riegrenades, or rockets), but it can also be mounted on differentprojectiles such as anti-personnel grenades, or incendiaries.

What is claimed is:

A fuse mechanism for mounting on the front of a hollow ohargeprojectile, comprising a deformable cylindrical envelope the base ofwhich is mounted on the projectile, a rigid support on the envelope and'an ogival cap on said support, said support having a peripheralhardened collar with a diameter approximately that of the envelope, aprimer-holder centrally mounted on said support, a truncated housing insaid primer-holder, said housing having a narrow base, a primer in saidprimerholder, said primer resting on the narrow base of said holder, aplunger rigidly mounted on the primer-holder,

a centering piece engaging the topof said primer, a spring between saidprimer and the wall of said truncated housing, a second support on ltheprojectile within said deformable ,envelope rearwardly of said firstsupport, a relay-detonator centrally disposed in said second support anda flexible member connecting said primer-holder to said relay-detonator.

References Cited in the file of this patent UNITED STATES PATENTS2,030,085 Woodberry Feb. 11, 1936 2,514,401 Liljegren July 1l, 19502,977,882 lasse Apr. 4, 1961 FOREIGN PATENTS 346,862 Italy Mar. 9, 1937577,815 Great Britain June 3, 1946 582,66() Great Britain lune 6, 1946614,381 Great Britain May 6, 1947 867,367 Germany Feb. 16, 1953

